Tft array substrate structure

ABSTRACT

The present invention provides a TFT array substrate structure, which includes first and second gates ( 11, 13 ), a semiconductor layer ( 20 ), first and second sources ( 31, 33 ), and first and second drains ( 42, 44 ). The first gate ( 11 ) and the first drain ( 42 ) are arranged to overlap in space so as to form a first overlapping zone (D). The second gate ( 13 ) and the second drain ( 44 ) are arranged to overlap in space so as to form a second overlapping zone (E). The first gate ( 11 ) has a first edge ( 113 ) corresponding to the first overlapping zone (D). The second gate ( 13 ) has a second edge ( 133 ) corresponding to the second overlapping zone (E). The first edge ( 113 ) and the first drain ( 42 ) intersect in space in an inclined manner. The second edge ( 133 ) and the second drain ( 44 ) intersect in space in an inclined manner. When the first and second drains ( 42, 44 ) are moved relative to the first and second gates ( 11, 13 ), areas of the first overlapping zone (D) and the second overlapping zone (E) undergo identical change.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to the field of liquid crystal displaying,and in particular to a TFT (Thin-Film Transistor) array substratestructure.

2. The Related Arts

Liquid crystal displays (LCDs) have a variety of advantages, such asthin device body, low power consumption, and being free of radiation,and are thus widely used, such as mobile phones, personal digitalassistants (PDAs), digital cameras, computer monitors, and screens ofnotebook computers.

A liquid crystal display generally comprises an enclosure, a liquidcrystal display panel arranged in the enclosure, and a backlight modulemounted in the enclosure. As shown in FIG. 1, a conventional liquidcrystal display panel comprises a TFT array substrate 100, a colorfilter (CF) substrate 300 located above and bonded to the TFT arraysubstrate 100, a liquid crystal layer 500 arranged the array substrate100 and the CF substrate 300, and a sealant frame 700 and the operationprinciple thereof is a drive voltage is applied between the TFT arraysubstrate 100 and the CF substrate 300 to control liquid crystalmolecules contained in the liquid crystal layer 500 to rotate so as torefract out the light from the backlight module to generate an image.

The liquid crystal display panels that are available in the main streammarket can be classified in three categories according to thearrangement of the liquid crystal molecules, which are TN (twistednematic)/STN (super twisted nematic), IPS (in-plane switching)/FFS(fringe field switching), and VA (Vertical Alignment), wherein the VAtype liquid crystal display has advantages, such as high contrast, wideview angle, and excellent color displaying. However, the VA type displayuses vertical rotation type liquid crystal, which shows color shift at alarge view angle. A known solution for such a phenomenon is to divide apixel zone into a main zone and a sub zone. Electrical voltage appliedto opposite sides of liquid crystal is different for the main zone andthe sub zone so that the rotation angle of the liquid crystal in themain zone and the sub zone is different thereby overcoming the colorshift problem.

As shown in FIG. 2, which shows a schematic view of a conventional TFT(Thin-Film Transistor) array substrate structure used in a VA typeliquid crystal display, the TFT array substrate structure comprisesfirst and second gates 101, 103, a semiconductor layer 200 arranged onthe first and second gates 101, 103, first and second sources 301, 303arranged on the semiconductor layer 200, and first and second drains402, 404 arranged on the semiconductor layer 200. The first and secondgates 101, 103 are electrically connected. The first and second sources301, 303 are electrically connected. The first gate 101 and the firstdrain 402 are arranged to overlap in space so as to form a firstoverlapping zone A and the first gate 101 has a first edge 105corresponding to the first overlapping zone A and perpendicularlyintersecting the first drain 402 in space. The second gate 103 and thesecond drain 404 are arranged to overlap in space so as to form a secondoverlapping zone B and the second gate 103 has a second edge 107corresponding to the second overlapping zone B and perpendicularlyintersecting the second drain 404 in space. A portion of the first drain402 that corresponds to the first overlapping zone A and a portion ofthe second drain 404 that corresponds to the second overlapping zone Bare each in the form of a strip, the two strips being arranged indirections that are perpendicular. The first source 301 is electricallyconnected to a data line; the first gate 101 is electrically connectedto a gate scan line; and the first and second drains 402, 404 arerespectively and electrically connected to a pixel electrode in a mainzone and a sub zone. The first overlapping zone A induces a firstparasitic capacitance and C_(gs) 1 and the second overlapping zone Binduces a second parasitic capacitance C_(gs) 2. With the direction ofstrip of the first drain 402 being taken as a vertical direction, whenthe first and second drains 402, 404 moved relative to the first andsecond gates 101, 103 in the vertical direction, the first overlappingzone A undergoes a change of the area thereof, while the secondoverlapping zone B maintain constant the area thereof so that the firstparasitic capacitance C_(gs) 1 changes but the second parasiticcapacitance C_(gs) 2 does not.

According to the feed-through voltage formula:

feed-through voltage ΔV=[C _(gs)/(C _(lc) +C _(s) +C _(gs))]×V _(p-p)

where C_(1c) is capacitance induced by a liquid crystal cell, C_(s) isstorage capacitance, C_(gs) is the capacitance value of a parasiticcapacitance induced between a gate and a drain, and V_(p-p) is voltagechange of the gate.

It can be appreciated that the first feed-through voltage ΔV1 changesbut the second feed-through voltage ΔV2 does not so that the voltagedifference between is changed, making reference voltage VCOM for therotation of liquid crystal molecules between the main zone and the subzone changed.

Similarly, when the first and second drains 402, 404 are moved relativeto the first and second gates 101, 103 in a horizontal direction, thearea of the first overlapping zone A remains unchanged, but the area ofthe second overlapping zone B changes, so that the first parasiticcapacitance C_(gs) 1 does not change but the second parasiticcapacitance C_(gs) 2 changes, thereby making the first feed-throughvoltage ΔV1 not change but the second feed-through voltage ΔV2 changed,eventually leading to a change of VCOM.

Instability of VCOM would causes problems of flickering and imagesticking occurring in a liquid crystal display panel thereby affectingthe displaying quality. It is apparently desired to have furtherimprovements over the known TFT array substrate structure.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a TFT (Thin-FilmTransistor) array substrate structure, in which two gates have portionscorresponding overlapping zones and having two edges that are arrangedto be inclined with respect to two drains so that when the drains aremoved relative to the gates, the changes of the areas of the twooverlapping zones are similar, allowing the reference voltage VCOM forrotation of liquid crystal molecules between main zones and sub zones ofsub-pixels to be maintained stable and providing the TFT array substrateand the structure is simple and easy achievement can be realized.

To achieve the above object, the present invention provides a TFT arraysubstrate structure, which comprises: first and second gates, asemiconductor layer arranged on the first and second gates, first andsecond sources arranged on the semiconductor layer, and first and seconddrains arranged on the semiconductor layer. The first and second gatesare electrically connected. The first and second sources areelectrically connected. The first gate and the first drain are arrangedto overlap in space so as to form a first overlapping zone. The secondgate and the second drain are arranged to overlap in space so as to forma second overlapping zone. The first gate has a first edge correspondingto the first overlapping zone. The second gate has a second edgecorresponding to the second overlapping zone. The first edge and thefirst drain intersect in space in an inclined manner and the second edgeand the second drain intersect in space in an inclined manner, so thatwhen the first and second drains are moved relative to the first andsecond gates, areas of the first overlapping zone and the secondoverlapping zone undergo change in the same direction.

The first and second drains are moved relative to the first and secondgates, the areas of the first overlapping zone and the secondoverlapping zone undergo identical change.

The inclination of the first edge with respect to the first drain is ina direction that is opposite to a direction of the inclination of thesecond edge with respect to the second drain.

The first drain has a portion corresponding to the first overlappingzone and in the form of a strip and the second drain has a portioncorresponding to the second overlapping zone and in the form of a strip.The two strips are respectively in directions that are perpendicular.

The first drain has a width W1 corresponding to the first overlappingzone and the second drain has a width W2 corresponding to the secondoverlapping zone. The first edge and the first drain define an acuteincluded angle α1=arccot(W2/W1). The second edge and the second draindefine an acute included angle α2=arccot(W1/W2).

The first source is in the form of a U-shape having an upward-facingopening and the second source is in the form of a U-shape having arightward-facing opening. The first source has a right portion connectedto a left portion of the second source.

The first drain extends into the U-shaped opening of the first sourceand the second drain extends into the U-shaped opening of the secondsource.

The TFT array substrate structure is applicable to a vertical alignmenttype liquid crystal display panel.

The TFT array substrate structure is applicable to a curved liquidcrystal display panel.

The present invention also provides a TFT array substrate structure,which comprises: first and second gates, a semiconductor layer arrangedon the first and second gates, first and second sources arranged on thesemiconductor layer, and first and second drains arranged on thesemiconductor layer, the first and second gates being electricallyconnected, the first and second sources being electrically connected,the first gate and the first drain being arranged to overlap in space soas to form a first overlapping zone, the second gate and the seconddrain being arranged to overlap in space so as to form a secondoverlapping zone, the first gate having a first edge corresponding tothe first overlapping zone, the second gate having a second edgecorresponding to the second overlapping zone, the first edge and thefirst drain intersecting in space in an inclined manner, the second edgeand the second drain intersecting in space in an inclined manner, sothat when the first and second drains are moved relative to the firstand second gates, areas of the first overlapping zone and the secondoverlapping zone undergo change in the same direction;

wherein when the first and second drains are moved relative to the firstand second gates, the areas of the first overlapping zone and the secondoverlapping zone undergo identical change;

wherein the inclination of the first edge with respect to the firstdrain is in a direction that is opposite to a direction of theinclination of the second edge with respect to the second drain;

wherein the first drain has a portion corresponding to the firstoverlapping zone and in the form of a strip and the second drain has aportion corresponding to the second overlapping zone and in the form ofa strip, the two strips being respectively in directions that areperpendicular;

wherein the first drain has a width W1 corresponding to the firstoverlapping zone and the second drain has a width W2 corresponding tothe second overlapping zone, the first edge and the first drain definingan acute included angle α1=arccot(W2/W1), the second edge and the seconddrain defining an acute included angle α2=arccot(W1/W2);

wherein the first source is in the form of a U-shape having anupward-facing opening and the second source is in the form of a U-shapehaving a rightward-facing opening, the first source having a rightportion connected to a left portion of the second source;

wherein the first drain extends into the U-shaped opening of the firstsource and the second drain extends into the U-shaped opening of thesecond source; and

wherein the TFT array substrate structure is applicable to a verticalalignment type liquid crystal display panel.

The efficacy of the present invention is that the present inventionprovides an array substrate structure, in which two gates have portionscorresponding overlapping zones and having two edges that are arrangedto be inclined with respect to two drains so that when the drains aremoved relative to the gates, the changes of the areas of the twooverlapping zones are similar, allowing the reference voltage VCOM forrotation of liquid crystal molecules between main zones and sub zones ofsub-pixels to be maintained stable and providing the TFT array substratewith a self-regulation function for VCOM thereby overcoming the problemsof flickering and image sticking occurring in a liquid crystal displaypanel resulting from unstable VCOM so as to enhance overall displayingquality.

For better understanding of the features and technical contents of thepresent invention, reference will be made to the following detaileddescription of the present invention and the attached drawings. However,the drawings are provided for the purposes of reference and illustrationand are not intended to impose undue limitations to the presentinvention.

BRIEF DESCRIPTION OF THE DRAWINGS

The technical solution, as well as other beneficial advantages, of thepresent invention will be apparent from the following detaileddescription of embodiments of the present invention, with reference tothe attached drawing. In the drawing:

FIG. 1 is a cross-sectional view showing of a conventional liquidcrystal display panel;

FIG. 2 is a schematic view showing the structure of a conventional TFT(Thin-Film Transistor) array substrate;

FIG. 3 is a schematic view showing a TFT array substrate structureaccording to the present invention;

FIG. 4 is a schematic view illustrating drains moved relative to gatesin a vertical direction, in which the solid lines indicate the conditionbefore the movement and the two-dashed phantom lines indicate thecondition after the movement; and

FIG. 5 is a schematic view illustrating drains moved relative to gatesin a horizontal direction, in which the solid lines indicate thecondition before the movement and the two-dashed phantom lines indicatethe condition after the movement.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

To further expound the technical solution adopted in the presentinvention and the advantages thereof, a detailed description is given toa preferred embodiment of the present invention and the attacheddrawings.

Referring to FIG. 3, the preset invention provides a TFT (Thin-FilmTransistor) array substrate structure, which comprises: first and secondgates 11, 13, a semiconductor layer 20 arranged on the first and secondgates 11, 13, first and second sources 31, 33 arranged on thesemiconductor layer 20, and first and second drains 42, 44 arranged onthe semiconductor layer 20. The first and second gates 11, 13 areelectrically connected. The first and second sources 31, 33 areelectrically connected. The first gate 11 and the first drain 42 arearranged to overlap in space so as to form a first overlapping zone D.The second gate 13 and the second drain 44 are arranged to overlap inspace so as to form a second overlapping zone E. The first gate 11 has afirst edge 113 corresponding to the first overlapping zone D. The secondgate 13 has a second edge 133 corresponding to the second overlappingzone E. The first edge 113 and the first drain 42 intersect in space inan inclined manner. The second edge 133 and the second drain 44intersect in space in an inclined manner. The inclination of the firstedge 113 with respect to the first drain 42 is in a direction that isopposite to a direction of the inclination of the second edge 133 withrespect to the second drain 44. In the instant embodiment, the firstedge 113 is inclined downward with respect to the first drain 42 in adirection from left to right and the second edge 133 is inclined upwardwith respect to the second drain 44 in a direction from left to right.

Thus, when the first and second drains 42, 44 are moved relative to thefirst and second gates 11, 13, areas of the first overlapping zone D andthe second overlapping zone E undergo change in the same direction.

Further, when the first and second drains 42, 44 are moved relative tothe first and second gates 11, 13, the areas of the first overlappingzone D and the second overlapping zone E undergo identical change.

The first drain 42 has a portion corresponding to the first overlappingzone D and in the form of a strip. The second drain 44 has a portioncorresponding to the second overlapping zone E and in the form of astrip. The two strips are respectively in directions that areperpendicular.

The first drain 42 has a width W1 corresponding to the first overlappingzone D and the second drain 44 has a width W2 corresponding to thesecond overlapping zone E. The first edge 113 and the first drain 42define an acute included angle α1=arccot(W2/W1) and the second edge 133and the second drain 44 define an acute included angle α2=arccot(W1/W2).

The first source 31 is in the form of a U-shape having an upward-facingopening and the second source 33 is in the form of a U-shape having arightward-facing opening. The first source 31 has a right portionconnected to a left portion of the second source 33.

The first drain 42 extends into the U-shaped opening of the first source31 and the second drain 44 extends into the U-shaped opening of thesecond source 33.

The first source 31 is electrically connected to a data line 50. Thefirst gate 11 is electrically connected to a gate scan line (not shown).The first drain 42 and the second drain 44 are electrically connected toa pixel electrode (not shown).

Referring to FIG. 4, with the direction of the strip of the first drain42 taken as the vertical direction, when the first and second drains 42,44 are moved upward, relative to the first and second gates 11, 13, inthe vertical direction, the area of the first overlapping zone D betweenthe first gate 11 and the first drain 42 is reduced and the area of thesecond overlapping zone E between the second gate 13 and the seconddrain 44 is also reduced correspondingly.

Assuming the amount of movement is V and the areas the first ad secondoverlapping zones D, E are respectively reduced by ΔS1, ΔS2, accordingarea formula of parallelogram, the following is obtained:

ΔS1=W1×V

ΔS2=W2×V×coα2

By combining with α2=arccot(W1/W2)

ΔS2=W2×V×(W1/W2)=W1×V

And, it is obtained that ΔS1=ΔS2

Similarly, when the first and second drains 42, 44 are moved downward,relative to the first and second gates 11, 13, in the verticaldirection, the area of the first overlapping zone D is enlarged and thearea of the second overlapping zone E is correspondingly enlarged by thesame amount.

Referring to FIG. 5, when the first and second drains 42, 44 are movedleftward relative to the first and second gates 11, 13 in a horizontaldirection, the area of the first overlapping zone D between the firstgate 11 and the first drain 42 is reduced and the area of the secondoverlapping zone E between the second gate 13 and the second drain 44 isalso reduced correspondingly.

Assuming the amount of movement is H and the areas of the second andfirst overlapping zones D, E are respectively reduced byΔS2′, ΔS1′,according area formula of parallelogram, the following is obtained:

ΔS2′=W2×H

ΔS1=W2×H×cotα1

By combining with α1=arccot(W2/W1)

ΔS1=W1×H×(W2/W/1)=W2×H

And, it is obtained that ΔS1′=ΔS2′

Similarly, when the first and second drains 42, 44 are moved rightwardrelative to the first and second gates 11, 13 in the horizontaldirection, the area of the first overlapping zone D is enlarged and thearea of the second overlapping zone E is correspondingly enlarged by thesame amount.

It can be seen that when the first and second drains 42, 44 undergorelative movement with respect to the first and second gates 11, 13, thechanges of the areas of the first overlapping zone D, the secondoverlapping zone E are of the same trend and the same amount so thatfirst parasitic capacitance C_(gs)l induced by the first overlappingzone D and second parasitic capacitance C_(gs) 2 induced by the secondoverlapping zone E are of changes of the same trend and same amount. Itcan be inferred from the feed-through voltage formula that a firstfeed-through voltage ΔV1 and a second feed-through voltage ΔV2 would beof the same trend and the same amount, meaning a voltage differencetherebetween is kept invariable, whereby the reference voltage VCOM forrotation of liquid crystal molecules between main zones and sub zones ofsub-pixels can be maintained relatively stable. Thus, the TFT arraysubstrate structure of the present invention is applicable to a verticalalignment type liquid crystal display panel and is also applicable to acurved liquid crystal display panel and also a vertical alignment typecurved liquid crystal display panel.

The present invention provides a TFT array substrate structure, in whichtwo gates have portions corresponding overlapping zones and having twoedges that are arranged to be inclined with respect to two drains sothat when the drains are moved relative to the gates, the changes of theareas of the two overlapping zones are similar, allowing the referencevoltage VCOM for rotation of liquid crystal molecules between main zonesand sub zones of sub-pixels to be maintained stable and providing theTFT array substrate with a self-regulation function for VCOM therebyovercoming the problems of flickering and image sticking occurring in aliquid crystal display panel resulting from unstable reference voltageVCOM of rotation of liquid crystal molecules so as to enhance overalldisplaying quality and being simple in structure and easy to achieve.

Based on the description given above, those having ordinary skills ofthe art may easily contemplate various changes and modifications of thetechnical solution and technical ideas of the present invention and allthese changes and modifications are considered within the protectionscope of right for the present invention.

What is claimed is:
 1. A thin-film transistor (TFT) array substratestructure, comprising: first and second gates, a semiconductor layerarranged on the first and second gates, first and second sourcesarranged on the semiconductor layer, and first and second drainsarranged on the semiconductor layer, the first and second gates beingelectrically connected, the first and second sources being electricallyconnected, the first gate and the first drain being arranged to overlapin space so as to form a first overlapping zone, the second gate and thesecond drain being arranged to overlap in space so as to form a secondoverlapping zone, the first gate having a first edge corresponding tothe first overlapping zone, the second gate having a second edgecorresponding to the second overlapping zone, the first edge and thefirst drain intersecting in space in an inclined manner, the second edgeand the second drain intersecting in space in an inclined manner, sothat when the first and second drains are moved relative to the firstand second gates, areas of the first overlapping zone and the secondoverlapping zone undergo change in the same direction.
 2. The TFT arraysubstrate structure as claimed in claim 1, wherein when the first andsecond drains are moved relative to the first and second gates, theareas of the first overlapping zone and the second overlapping zoneundergo identical change.
 3. The TFT array substrate structure asclaimed in claim 1, wherein the inclination of the first edge withrespect to the first drain is in a direction that is opposite to adirection of the inclination of the second edge with respect to thesecond drain.
 4. The TFT array substrate structure as claimed in claim3, wherein the first drain has a portion corresponding to the firstoverlapping zone and in the form of a strip and the second drain has aportion corresponding to the second overlapping zone and in the form ofa strip, the two strips being respectively in directions that areperpendicular.
 5. The TFT array substrate structure as claimed in claim4, wherein the first drain has a width W1 corresponding to the firstoverlapping zone and the second drain has a width W2 corresponding tothe second overlapping zone, the first edge and the first drain definingan acute included angle α1=arccot(W2/W1), the second edge and the seconddrain defining an acute included angle α2=arccot(W1/W2).
 6. The TFTarray substrate structure as claimed in claim 1, wherein the firstsource is in the form of a U-shape having an upward-facing opening andthe second source is in the form of a U-shape having a rightward-facingopening, the first source having a right portion connected to a leftportion of the second source.
 7. The TFT array substrate structure asclaimed in claim 6, wherein the first drain extends into the U-shapedopening of the first source and the second drain extends into theU-shaped opening of the second source.
 8. The TFT array substratestructure as claimed in claim 1, wherein the TFT array substratestructure is applicable to a vertical alignment type liquid crystaldisplay panel.
 9. The TFT array substrate structure as claimed in claim1, wherein the TFT array substrate structure is applicable to a curvedliquid crystal display panel.
 10. A thin-film transistor (TFT) arraysubstrate structure, comprising: first and second gates, a semiconductorlayer arranged on the first and second gates, first and second sourcesarranged on the semiconductor layer, and first and second drainsarranged on the semiconductor layer, the first and second gates beingelectrically connected, the first and second sources being electricallyconnected, the first gate and the first drain being arranged to overlapin space so as to form a first overlapping zone, the second gate and thesecond drain being arranged to overlap in space so as to form a secondoverlapping zone, the first gate having a first edge corresponding tothe first overlapping zone, the second gate having a second edgecorresponding to the second overlapping zone, the first edge and thefirst drain intersecting in space in an inclined manner, the second edgeand the second drain intersecting in space in an inclined manner, sothat when the first and second drains are moved relative to the firstand second gates, areas of the first overlapping zone and the secondoverlapping zone undergo change in the same direction; wherein when thefirst and second drains are moved relative to the first and secondgates, the areas of the first overlapping zone and the secondoverlapping zone undergo identical change; wherein the inclination ofthe first edge with respect to the first drain is in a direction that isopposite to a direction of the inclination of the second edge withrespect to the second drain; wherein the first drain has a portioncorresponding to the first overlapping zone and in the form of a stripand the second drain has a portion corresponding to the secondoverlapping zone and in the form of a strip, the two strips beingrespectively in directions that are perpendicular; wherein the firstdrain has a width W1 corresponding to the first overlapping zone and thesecond drain has a width W2 corresponding to the second overlappingzone, the first edge and the first drain defining an acute includedangle α1=arccot(W2/W1), the second edge and the second drain defining anacute included angle α2=arccot(W1/W2); wherein the first source is inthe form of a U-shape having an upward-facing opening and the secondsource is in the form of a U-shape having a rightward-facing opening,the first source having a right portion connected to a left portion ofthe second source; wherein the first drain extends into the U-shapedopening of the first source and the second drain extends into theU-shaped opening of the second source; and wherein the TFT arraysubstrate structure is applicable to a vertical alignment type liquidcrystal display panel.